Drive-In and Drive through Racks-Forklift drives directly into the lane of stacked rows (bays). Drive-In has only one opening so mainly used for LIFO (Last In First Out) operation. Drive-through has two openings so used for FIFO (First In First Out) operation where loading is done from one side & unloading is done from the other side. Advantageous for material with an expiration date or shelf life is of concern.